Many patients with cystic fibrosis (CF) cough up mucus or have throat cultures that grow a common fungus called Aspergillus. In patients with CF, aspergillus is not known to cause direct damage to the lungs, but some patients respond with an allergic reaction that causes them to wheeze, cough, or have difficulty breathing. This allergic reaction is called ABPA. Current treatment for ABPA includes high dose steroids and an "anti-fungal" medicine. Treatment with steroids may be problematic for some people due to its side effects on blood sugar levels and the bones. Steroids are medications that decrease inflammation, including prednisone, medrol, dexamethasone and others.